research papers Acta Cryst. (2019). C75, 891–903 https://doi.org/10.1107/S205322961900682X 891 Received 17 January 2019 Accepted 12 May 2019 Edited by V. Langer, Chalmers University of Technology, Sweden 1 Presented in part to the 1st International Electronic Conference on Crystals (IECC 2018). Keywords: 1,2,3-triazole; metal complex; crystal structure; supramolecular architecture; hydrogen bonding; noncovalent interactions; stacking interactions. CCDC references: 1837084; 1915706; 1837083; 1849847 Supporting information: this article has supporting information at journals.iucr.org/c Design and synthesis of methyl 2-{[4-phenyl-5- (pyridin-2-yl)-4H-1,2,4-triazol-3-yl]sulfanyl}acetate (phpy2NS) as a ligand for complexes of Group 12 elements: structural assessment and hydrogen- bonded supramolecular assembly analysis 1 Alfonso Castin ˜eiras,* Isabel Garcı ´a-Santos and Manuel Saa Department of Inorganic Chemistry, Faculty of Pharmacy, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain. *Correspondence e-mail: alfonso.castineiras@usc.es The reaction of 2-cyanopyridine with N-phenylthiosemicarbazide afforded 2-[amino(pyridin-2-yl)methylidene]- N-phenylhydrazine-1-carbothioamide (Ham4ph) and crystals of 4-phenyl-5-(pyridin-2-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (pyph3NS, 1,C 13 H 10 N 4 S). Crystals of methyl 2-{[4-phenyl-5-(pyridin-2-yl)-4H- 1,2,4-triazol-3-yl]sulfanyl}acetate (phpy2NS, 2,C 16 H 14 N 4 O 2 S), derived from 1, were obtained by the reaction of Ham4ph with chloroacetic acid, followed by the acid-catalyzed esterification of the carboxylic acid with methyl alcohol. Crystals of bis(methanol-O)bis(methyl 2-{[4-phenyl-5-(pyridin-2-yl)-4H-1,2,4- triazol-3-yl- 2 N 1 ,N 5 ]sulfanyl}acetato)zinc(II)/cadmium(II) hexabromidocad- mate(II), [Zn 0.76 Cd 0.24 (C 16 H 14 N 4 O 2 S) 2 (CH 3 OH) 2 ][Cd 2 Br 6 ] or [Zn 0.76 Cd 0.24 - (phpy2NS) 2 (MeOH) 2 ][Cd 2 Br 6 ], 3, and dichlorido(methyl 2-{[4-phenyl-5-(pyridin- 2-yl)-4H-1,2,4-triazol-3-yl- 2 N 1 ,N 5 ]sulfanyl}acetato)mercury(II), [HgCl 2 (C 16 - H 14 N 4 O 2 S)] or [Hg(phpy2NS)Cl 2 ], 4, were synthesized using ligand 2 and CdBr 2 or HgCl 2 , respectively. The molecular and supramolecular structures of the compounds were studied by X-ray diffractometry. The asymmetric unit of 3 is formed from CdBr 3 and M(phpy2NS)(MeOH) units, where the metal centre M has a 76% occupancy of Zn II and 24% of Cd II . The M 2+ centre of the cation, located on a crystallographic inversion centre, is hexacoordinated and appears as a slightly distorted octahedral [MN 4 O 2 ] 2+ cation. The Cd centre of the anion is coordinated by two terminal bromide ligands and two bridging bromide ligands that generate [Cd 2 Br 6 ] 2 cadmium–bromide clusters. These clusters display crystallographic inversion symmetry forming two edge-shared tetrahedra and serve as agents that direct the structure in the formation of supramolecular assemblies. In mononuclear complex 4, the coordination geometry around the Hg 2+ ion is distorted tetrahedral and comprises two chloride ligands and two N- atom donors from the phpy2NS ligand, viz. one pyridine N atom and the other from triazole. In the crystal packing, all four compounds exhibit weak intermolecular interactions, which facilitate the formation of three-dimensional architectures. Along with the noncovalent interactions, the structural diversity in the complexes can be attributed to the metal centre and to the coordination geometry, as well as to its ionic or neutral character. 1. Introduction Thiosemicarbazones continue to attract attention, not only as multifunctional ligands (Casas et al. , 2000), but also because they can undergo ring-closure processes by the action of bases, acids or oxidants. Reactions may follow different routes depending on the open-chain substrate (thiosemicarbazone) structure and on the nature of the cyclizing agent. Metal cations represent an interesting class of oxidizing agents (Lo Meo et al. , 2005). Oxidative cyclization of thiosemicarbazones ISSN 2053-2296 # 2019 International Union of Crystallography